Infectious Diseases Flashcards
what is septic shock
- arterial blood pressure drops despite adequate fluid resuscitation, resulting in organ hypoperfusion.
- Anaerobic respiration begins, and lactate level rises.
It is diagnosed with: - Low mean arterial pressure (below 65 mmHg) despite fluid resuscitation (requiring vasopressors)
- Raised serum lactate (above 2 mmol/L)
Mx of septic shock
- aggressive IV fluids
- HDU
- vasopressors e.g. noradrenaline (cause vasoconstriction)
Rf for sepsis
- immune dysfunction
- frailty and very young
- chronic conditions (COPD, diabetes)
- chemo, immunosuppressants
- surgery, trauma, burns
- pregnancy
- catheter, central lines
Bloods for sepsis
- FBC for WCC + neutrophils
- U&Es for kidney function + AKI
- LFTs for liver function and a possible source of infection
- CRP for inflammation
- Blood glucose for hyper/hypoglycaemia
- Clotting to assess for disseminated intravascular coagulopathy (DIC)
- Blood cultures to assess for bacteraemia
- Blood gas for lactate, pH and glucose
additional test for sepsis to locate source
- urine dipstick
- chest XR
- CT abdo
- LP
what is neutropenic sepsis
absolute neutrophil count below 0.5 x 109/L (or likely to fall to this level). It is a life-threatening medical emergency
Mx of neutropenic sepsis
immediate broad-spectrum antibiotics, such as piperacillin with tazobactam (tazocin)
Pyelonephritis sx
LUTI sx + triad
- loin to groin/back pain
- fever
- N&V
(renal angle tenderness)
when is MSU important in UTI
- pregnancy
- recurrent UTI
- atypical sx
- sx not improving on abx
Mx of LUTI
- Nitrofurantoin (avoided in patients with an eGFR <45)
- Trimethoprim (often associated with high rates of bacterial resistance)
can also go amoxicillin, cefalexin
3 days simple, 7 if man/pregnant, 5-10 days kidneys/immunosuppressed
Mx of pyelonephritis
first-line abx 7-10 days when treating in the community:
- Cefalexin
- Co-amoxiclav (if culture results are available)
- Trimethoprim (if culture results are available)
- Ciprofloxacin (keep tendon damage and lower seizure threshold in mind)
SEPSIS 6 if in hospital
what to consider if pyelonephritis not improving
- renal abscess
- kidney stone
Mx of UTI in pregnancy
7 days + MSU
- Nitrofurantoin (avoided in the third trimester due to neonatal haemolysis)
- Cefalexin
- Amoxicillin (only after sensitivities are known)
avoid trimeth in 1st as folate antagonist (neural tube)
causes of cellulitis
- Staphylococcus aureus
- Group A streptococcus (mainly streptococcus pyogenes)
- Group C streptococcus (mainly streptococcus dysgalactiae)
- consider MRSA
Mx of cellulitis
- flucloxacillin 1st line
- clarithromycin
- clindamycin
- co-amoxiclav if near eyes/nose
common bacterial causes of intra-abdominal infections
- Anaerobes (e.g. Bacteroides and Clostridium)
- E. coli (gram-negative)
- Klebsiella (gram-negative)
- Enterococcus (gram +ve)
- Streptococcus (gram +ve)
Mx of intra-andominal infections
need broad spectrum e.g.
- co-amoxiclav
- quinolones
- metronidazole
- gentamicin
- vancomycin
- cephalosporins
- tazocin
Mx of septic arthritis
- joint aspiration
- empirical IV abx for 4-6 wks
e.g. fluclox, clinda, vanc, ceftriaxone (gonorrhoea)
Mx for influenza in people at risk
- Oral oseltamivir (BD for 5 days)
- Inhaled zanamivir (BD for 5 days)
start within 48hrs of sx onset
causes of viral gastroenteritis
- rotavirus
- norovirus
- adenovirus
- E coli 0157 (bloody)
- campylobacter jejuni (MC worldwide, raw poultry)
Shigella
- spread by faeces or contaminated water/food
- incubation 1-2 days
- Mx: azithromycin
Salmonella
- raw eggs, poultry
- incubation 12hrs-3days
- sx resolve within 1 week
Bacillus cereus
- gram +ve rod
- reheated rice
- watery dirahhoea
how to diagnose C.diff
Stools can be tested for:
- C. difficile antigen (specifically glutamate dehydrogenase)
- A and B toxins (by PCR or enzyme immunoassay)
Mx of c.diff
- oral vancomycin (1st)
- oral fidaxomicin (2nd)
if serious oral van and IV metronidazole?
If recurrence <12 weeks oral fidaxomicin if >12 weeks van
complications of c.diff
- pseudomembranous colitis: inflam of large intestine with yellow/white plaques that form pseudomembranes on the inner surface of the bowel wall
- toxic megacolon
causes of meningitis
- Neisseria meningitidis
- Strep pneumoniae (pneumococcus)
- Haemophilus influenzae
- Group B streptococcus (GBS) (particularly in neonates)
- Listeria monocytogenes (particularly in neonates)
what is meningococcal septicaemia
non-blanching rash
tests for meningeal infection
- kernig’s test
- Brudzinski’s test
LP in bacterial and viral meningitis
Bacterial: cloudy, high protein, low glucose, high neutrophils
Viral: clear, mildly raised/normal protein, normal glucose, high lymphocytes
complication of meningitis
- hearing loss
- seizures and epilepsy
- cognitive impairment
staining for TB
Zeihl-Neelsen stain, which turns them bright red against a blue background.
Ix for TB
- Mantoux test
- Interferon‑gamma release assay (IGRA)
- 3 sputum cultures
Mx of TB
Rifampicin 6 months
Isoniazid 6 months
Pyrazinamide 2 months
Ethambutol 2 months
side effects of TB treatment
- Rifampicin: red/orange secretions
- Isoniazid: peripheral neuropathy (prescribe pyridoxine (vit b6) to reduce risk)
- Pyrazinamide: hyperuricaemia resulting in gout and kidney stones
- Ethambutol: colour blindness, reduced visual acuity
RIP all assoc with hepatotoxicity
examples of AIDS defining illnesses
when CD4 is low
- Kaposi’s sarcoma
- Pneumocystis jirovecii pneumonia (PCP)
- Cytomegalovirus infection
- Candidiasis (oesophageal or bronchial)
- Lymphomas
- Tuberculosis
classes of antiretroviral therapy for HIV
- Protease inhibitors (PI)
- Integrase inhibitors (II)
- Nucleoside reverse transcriptase inhibitors (NRTI)
- Non-nucleoside reverse transcriptase inhibitors (NNRTI)
- Entry inhibitors (EI)
usually 2NRTIs + third agent
additional mx of HIV
- prophylactic co-trimoxazole when CD4 <200 to protect against PCP
presentation of malaria
- cyclic fever up to 41, sweats and rigors
- myalgia
- N/V, fatigue, headache
- hepatosplenomegaly
- jaundice
- pallor
how to diagnose malaria
blood film
mx of malaria
- Artemether with lumefantrine (Riamet) is the usual first choice
- Quinine plus doxycycline
- Quinine plus clindamycin
- Proguanil with atovaquone (Malarone)
- Chloroquine
- Primaquine (can cause severe haemolysis in patients with G6PD deficiency)
- severe: artesunate
cryptosporidium parvum features
- protozoan parasite
- cause diarrhoea in immunocompromised patients
- found in contaminated water sources
- test: modified Ziehl–Neelsen stain/ Kinyoun Acid Fast stain
- Mx: Paromomycin
Abx for MRSA +ve cellulitis
vancomycin
late stage HIV presentation
- folliculitis on chest
- also fauces are red and there are two small aphthous ulcers on his left buccal mucosa. He also has a maculopapular erythematous rash on his upper trunk, red hands
gram +ve bacteria
- pair: strep pneumoniae
- clusters: staph aureus
how does herpes simplex virus present
- hsv1: cold sore
- hsv 2: multiple tender ulcers on the preputial skin
hepatitis B presentation
most commonly presents with anorexia, nausea and right upper quadrant pain
typhoid fever presentation
- Salmonella typhi g-ve rods
- faeco-oral transmission
- headache, fever, arthralgia
- constipation
- rose spots
mx of typhoid
IV ceftriaxone then PO
azithromycin
which organism causes erythema multiforme (target lesions)
mycoplasma pneumoniae
campylobacter jejuni presentation and mx
- undercooked poultry
- bloody diarrhoea
- mx erythromycin
giardia presentation and mx
- watery foul smelling stool
- swimming in lake
- pear shaped trophozoite
- mx metronidazole
C difficile mx
- oral vancomycin 10 days
- 2nd line fidaxomicin
- severe: oral vancomycin + IV metronidazole
recurrence
<12 weeks: oral fidaxomicin
>12 weeks: oral vanc or fidax
who should receive hepatitis A vaccine
- MSM
- Close contacts of infected persons
- Travellers to common countries
- People with chronic liver disease
- Injecting drug users
- People with haemophilia
- High-risk of occupational hepatitis A exposure e.g. sewage workers, people who work for organisations where personal hygiene may be poor (e.g. homeless shelters), and people working with primates
lyme disease features
- tick (Borrelia burgdoferi)
- erythema chronicum migrans (bullseye rash
- flu like sx
- Late persistent: focal neurology, neuropsychiatric, arthritis
- Mx doxycycline
- if ticket removed and well no prophylactic abx needed
infectious mononucleosis presentation
Triad of:
- sore throat, pyrexia and lymphadenopathy
Also
- palatal petechiae
- malaise
- a maculopapular, pruritic rash if pts take ampicillin/amoxicillin whilst they have infectious mononucleosis
Diagnosis of infectious mononucleosis
monospot test
mx of infectious mononucleosis
- rest and analgesia
- avoid contact sport for 4 weeks
chlamydia features
asymptomatic in around 70% of women and 50% of men
women: cervicitis (discharge, bleeding), dysuria
men: urethral discharge, dysuria
complications of chlamydia
epididymitis
pelvic inflammatory disease
endometritis
increased incidence of ectopic pregnancies
infertility
reactive arthritis
perihepatitis (Fitz-Hugh-Curtis syndrome)
ix for chlamydia
NAAT
for women: the vulvovaginal swab is first-line
for men: the urine test is first-line
do 2 weeks post exposure
Mx of chlamydia
doxycycline 7 days
if pregnant then azithromycin, erythromycin or amoxicillin
Presentation of gonorrhoea
- Gram-negative diplococcus
- males: urethral discharge, dysuria
- females: cervicitis e.g. leading to vaginal discharge
- rectal and pharyngeal infection is usually asymptomatic
complications of gonorrhoea
- urethral strictures
- epididymitis
- salpingitis- may lead to infertility
- Disseminated infection may occur
mx of gonorrhoea
- single dose of IM ceftriaxone 1g
- if can’t take give azithromycin
